Coded track circuits for highway



7 pril 6; 1948. A. L.JEROM 2,439,006

CODED TRACK CIRCUITS FOR HIGHWAY CROSSING SIGNALS Filed Nov. 18, 1944 IN VENTOR F' .5. Amlzar'LJe m [H ay BY c;

3 1508 ATTORNEY Patented Apr. 6, 1948 CODED TRACK CIRCUITS FOR HIGHWAY CROSSING SIGNALS I Arthur L. Jerome, Edgewood, Pa., assignor to The. Union Switch & Signal Company, Swissvale, Pa., a corporation 01' Pennsylvania Application November 18, 1944, Serial N... 564,144.

My invention relates to railway signaling apparatus and particularly to improved. means for indicating occupancy of the portion of a section in advance of an intermediate point in a section.

This application is a continuation-in-part of my application Serial No. 501,204, filed September4, 1943, for Coded track circuits, now Patent No. 2,376,967, issued May 29, 1945.

It has heretofore been proposed to provide for a section of railway track, a track circuit comprising a code following track relay at the entrance end of the track section together with means at the exit end of the section for supplying to the track relay over the section rails impulses of master code which are separated by intervals during which no energy is supplied. In addition, it has been proposed to provide means associated with the track relay for supplying to the section rails in the intervals between impulses of master code, impulses of feed-back energy which operate a feed-back detector relay at the exit end of the section or at some other advanced location in the track section, to provide an indication of occupancy of the track section.

An object of this invention is to provide an improved coded track circuit of the type described and incorporating means to maintain operation of the feed-back detector relay until a train advances beyond a predetermined point in the track section.

A further object of the invention is to provide an improved coded track circuit incor rating means to indicate'occupancy of the forward portion only of a track section.

Another object of the invention is to provide an improved coded track circuit incorporating means to indicate occupancy of anintermediate portion only of a track section.

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings.

I shall describe two forms of railway signaling apparatus embodying my invention and shall then point out the novel features thereof in claims.

In practicing my invention I provide means at the exit end ofa track section for supplying to the section rails impulses of master code to oper- "7 Claims. (01.246-130) end of the track section, while the track relay has associated therewith means for supplying to the section rails in the intervals between impulses of master code, impulses of feed-back energy which operate a feed-back detector relay at the exit end or other advanced point in the track section. In addition, there is provided means eifective when the track relay is not responding to coded energy to supply to the section rails at a selected point in the section in advance of the entrance end of the section impulses of coded energy which will operate the feed-back detector relay until a train advances beyond the selected point in the section.

moves in the direction indicated by the arrow,

that is from left to right. The rails of the track section are separated from the rails of the adjoining track sections by insulated joints 3.

A code following track relay TB. is connected across the section rails at the entrance end of i the section, while this relay is operated by master code supplied over the section rails from the track battery TB at the exit end of the section. The supply of energy from the track battery to the section rails is controlled by a coding relay CR which may be governed in any manner well known in the art by traffic conditions in the adjacent section in advance. In a typical system the relay CR may be operated to supply energy of code frequency to the section railswhen the adjacent section in advance is occupied and to supply energy of code frequency to the section rails when the adjacent section in advance is vacant.

The track relay TR and the feed-back detector relay K each has associated therewith a source of direct current, not shown, the terminals of which are designated B and C in the drawings.

ate the code following track relay at the entrance 50 The track section includes an intersection with a highway, while an insulated joint I is located in one or the track rails at a po nt adjacent the highway crossing. The detector relay K has one terminal of its winding connected to the track rail at one side of the insulated joint 5 while the other terminal of the relay winding is connected to the track rail at the other side of the insulated joint. The relay K controls the supply of energy through a decoding transformer KT to a relay KP which may be employed to control crossing signals XS for warning users of the highway of the approach of a train. -The relay KP may control the crossing signals directly, or it may control them indirectly through auxiliary track circuit apparatus of the type shown in my application for Letters Patent of the United States Serial No. 471,838, now Patent No. 2,409,044, issued October 8, 1946.

The highway crossing is located in the track section at a point such that it is desired not to initiate operation of the crossing signals until a train advances some distance beyond the entrance end of the track section. An insulated joint 6 is located in track rail 2 at the point in the track section at which it is desired to initiate operation of the crossing signals, while a code transmitter CT is located at the joint 6 and is provided with a movable contact I6 which is biased to a position in which it establishes a connection around the joint 6. When the winding of the device CT is energized, the contact I6 is recurrently moved to a position in which it connects an auxiliary feed-back battery around the joint 6. The code transmitter CT is controlled by relay H by a line circuit.

When the contact I 0 of coding relay CR is moved .to its picked-up position the track battery TB is connected across the section rails with the positive terminal of the battery connected to track rail I. Accordingly, master code energy flows from the positive terminal of the battery over contact Iii of relay CR, track rail I, winding of track relay TR from left to right, back contact I! of relay IR, track rail 2, back contact it of coding device CT, winding of relay K from left to right, and track rail 2 to the negative terminal of the battery TB. v

The track relay TB is of the polar biased type the contact of which picks up when and only when energy flows through the relay winding in a. particular direction, while the track relay is connected in the track circuit so that its contact picks up when energy flows through the relay winding from left to right which is the direction in which energy from the track battery flows through thewinding of the track relay.

The relay K is also of the polar biased type and is connected in the track circuit in such manner that the relay contacts pick up only when energy flows through the relay winding from right to left. Accordingly, when contact ll) of relayCR picks up to cause energy to be supplied from the track battery to the section rails, energy flows through the windings of relays TR and K, while this energy will pick up the track rail 1, back contact Ill of relay CR, track rail 2, winding of relay K from right to left, back contact iii of code transmitter CT, and track rail 2 to the negative terminal of the battery FIB. The energy supplied from battery FB flows through the winding of relay TR. in the wrong direction to pick up the relay contacts-so the track relay contacts remain released at this time. The energy supplied from the battery FB flows through the winding of relay K in the right direction to pick up its contacts so the contacts contact of relay TR, but will not pick up the v contacts of relay K.

On movement of the contact of relay CR to its released position, the supply of energy from the track battery to the section rails is cut off, and

contact I0 establishes connection between the of relay K pick up on the supply of an impulse of feed-back energy to the section rails. Accordingly, as long as the section is vacant the track relay TR is operated by master code supplied over the section rails, whilethe relay K is operated by feed-back energy supplied over the section rails.

As a result of code following operation of the track relay TR energy is supplied through the decoding transformer DT to relays H and IR and the contacts of relay H are maintained picked up, while relay IR. operates to supply impulses of feed-back energy to the section rails. The relay H may be employed in the well-known manner to control the signal for the track section and to control the supply of coded energy to the rails of the adjacent section in the rear, while a contact of relay H when picked up interrupts' the circuit of code transmitter CT so that its contact l6 remains released and maintains the connection around insulated joint 6.

As a result of code following operation of relay K energy is supplied through the decoding transformer KT to relay KP to maintain the contacts of relay KP picked up and prevent operation of the crossing signals XS. In addition, on picking up of the relay K a contact M of the relay estab- 1 lishes a circuit to supply an impulse of energy from a secondary winding of transformer KT to a local winding of relay K, The various parts of the apparatus are arranged so that the energy supplied from the transformer KT to relay K is of the same polarity as the energy supplied from the feed-back battery to the track winding of the relay and aids the energy supplied to the track winding of the relay to maintain the relay contacts picked up. The energy supplied from the transformer KT to the relay K prolongs the picked-up periods of the relay enough to insure that sufficient energy is supplied from transformer KT to relay KP even though the impulse of feed-back energy are relatively short.

When a train moving in the normal direction of traflic enters the track section, the track relay TR ceases to follow code and relay H releases and relay 1R ceases to cause feed-back energy from battery F3 to be supplied to the section rails. On release of relay H energy is supplied to coding device CT and its contact I6 is Picked up and released at any appropriate rate, such as times a minute, which is different from the rates of operation of relay CR.

When contact I6 picks up, energy flows from the positive terminal of battery FBA over front contact l6, rail 2, through the wheels and axles of the vehicles of the train to rail I, over back contact I0 of relay CR, rail 2, and .winding of relay K to the negative terminal of the battery FBA. This energy operates relay K and keeps relay KP- picked up to prevent operation of the crossing signals XS.

Although energy is supplied from battery FBA to relay K only when the contact l6 of coding device CT is picked up and contact of coding relay GR is released, there are frequently recurring periods during which these contacts are in this relationship so suilicient energy is supplied to relay KP to keep its contacts picked up.

when the train advances beyond the joint 6 it shunts the relay K with respect to energy from battery FBA so relay K ceases to operate and relay KP releases to initiate operation of the crossing signals XS.

When the rear of the train advances beyond joint 6 energy from battery FBA flows through the track relay TR, but this energy flows through the track relay winding in the wrong direction to operate the track relay and its contact remains released so relay H remains released and maintains the circuit of coding device CT.

When the rear of the train advances beyond joint energy from battery FBA again feeds to relay K and operates it to pick up relay KP to discontinue operation of the crossing signals XS.

When the train vacates the track section, master code energy from the track battery TB feeds to the track relay TR at a time when contact iii of coding device CT is released and picks up the track relay so that energy is supplied to relay tion of coding device CT, while energy is supplied to relay IR so that it operates to cause feed-back energy to be supplied from battery F3 to operate relay K and maintain relay KP picked up to prevent operation of the crossing signals.

The modification shown in Fig. 1, therefore, is arranged so that when a train enters the section, feed-back energy is supplied to the section rails at an intermediate point in the section to prevent operation of the crossing signals until the train advances beyond this point in the section. If for any reason the means for supplying feedback energy to the section rails at the intermediate point in the section is inoperative, the crossing signals will start to operate as soon as the train enters the section and users of the highway will have longer than usual warning of the approach of a train.

In Fig. 2, there is shown a modified arrangement of apparatus which may be employed at the entrance end of a track section in place of that shown in Fig. l.

Referring to Fig. 2 it will be seen that the impulse relay IR and the feed-back battery FB are located adjacent the insulated joint 6 in track rail 2, and that contact l2 of relay IR when released establishes connection around the insulated joint 6. The relay IR is controlled over a line circuit from the entrance end of the section, and at times is operated by energy supplied from a secondary winding of the decoding transformer and at other times is operated by energy supplied over a circuit controlled by the coding device CT.

When the section is vacant, master code energy supplied at the exit end of the section feeds over the section rails and over back contact H of relay IR to the track relay TR and picks up the track H to pick up its contacts and discontinue opera- During the off periods in the master code,

the track relay contacts release and an impulse of energy is supplied from a secondary winding of the decoding transformer over a front contact of relay H to the relay IR andithe contact 12 of relay IRpicks up momentarily. When contact I! of relay IR is picked up, the battery F3 is connected around the insulated Joint 6 with the result that energy flows from the positive terminal of this battery over front contact l2 of relay IR to the portion of rail 2 in the rear of Joint 6 and through the winding of track relay TR. from right to left to track rail I, and thence to the detector relay K as explained in connection with Fig. 1. The energy supplied from battery FB flows through the track relay winding in the wrong direction to pick up the relay contacts, but is of the proper polarity to operate the detector relay K and it causes energy to be supplied through the transformer KT to the relay KP.

When a train moving in the normal direction of traflic enters the section, the track relay TR ceases to follow code and relay H releases to interrupt the circuit for supplying energy from a secondary winding of transformer DT to relay IR and establishes the circuit controlled by the coding device 01 for supplying energy to the relay IR. Accordingly, the relay IR continues to operate so that the positive terminal of the battery F5 is connected to the portion of rail 2 in the rear of joint .6, and energy supplied to this rail feeds through the wheels and axles: of the vehicles of the train to rail i and thence to de tector relay K to maintain relay KP picked up to prevent operation of the crossing signals.

When the train advances beyond the insulated joint 6, the relay K is shunted with respect to energy from the battery FE and ceases to operate so that relay KP releases and initiates operation of the crossing signals XS.

When the train advances far enough for the rear of the train to be located in advance of the Joint 5, energy from battery FB again operates the relay K so that relay KP picks up and discontinues operation of the crossing signals. When the train vacates the section, master code energy feeds to the track relay TR during a released period of the contact I! of relay IR and operates the track relay to pick up the relay H to interrupt the circuit controlled by the code transmitter CT for energizing the relay IR and ,to establish the circuit for supplying energy from In the modification shown in Fig. 3 a coding relay CR is operated at rates governed by traffic in advanceand when its contacts are picked up the secondary winding of a track transformer is connected across the section rails so that energy is supplied-to the track relay TR over the section rails and over normally closed back contacts of coding device CT. The alternating current energy is supplied from a suitable source the terminals of which are designated BX and CK. The track relay TR is connected across the section rails through a rectifier and a transformer by a circuit controlled by back contacts of the relay IR. On release of the contacts of coding relay CR the supply of energy from the track transformer to the section rails is cut oil and relay AB. .is connected across the section rails through a suitable transformer and rectifier. At this time the track relay releases and the relay 13 picks up momentarily to interrupt the circuit of the track relay and to connect a feed-back transformer FBT across the section rails so that an impulse of feed-back energy is supplied to relay AR and picks up its contacts.

On continued operation of the relay CR the track relay follows code so that relay H is picked up and interrupts the circuit of coding device CT, while relay IR. supplies feed-back energy over the section rails -,-so that relay AR follows code and keeps relay AP picked up to prevent opera-,

tion of the crossing signals XS.

When a train moving in the normal direction of trafflc enters the track section the track relay ceases to follow-code and relay H releases so that coding device CI is 'operated to interrupt the connection between the track rails on opposite sides of the insulated joints 8 and to connect the transformer FBTA across the track rails in advance of the joints 8. The energy supplied from transformer FBTA feeds to relay AR during the released periods of relay CR and operates relay AR "to maintain relay AP picked up and prevent operation of the crossing signals XS. The coding device CT operates at a substantially different speed than the rates at which relay CR is operated so there are frequently recurring periods during which energy is supplied to relay AR and it is certain to operate to maintain relay AP i picked up.

When the train advances beyond the Joints 6 i the relay AR is shunted with respect to energy supplied from transformer FBTA, and ceases to operate so that relay-AP releases and causes the crossing signals XS to operate.

When the section is vacated energy from the transformer TT feeds to the track relay TR during released periods of the coding device CT and operates the track relay so that relay H is picked up to discontinue operation of coding device CT, while relay IR operates to supply feed-back energy to the section rails to operate relay AR and pick up relay AP and discontinue operation of the crossing signals.

Although the track circuits provided by this invention have "been illustrated and described in connection with the control of highway crossing signals, the invention is not limited to use for this purpose but may be employed for other purposes, as for example, to control locking of a switch at an intermediate point in a track section.

. Although I have illustrated and described several forms of railway signaling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims 8 1 terminal of the source connected to the first r k l a code following track relay at the other end of said track section operated by energy supplied over the section rails from said first source. means associated with said track relay and operative during the intervals between the impulses of energy supplied from said first source to eifectlvely connect a second source of only when said auxiliary relay is released, a de-- tector relay having a winding connected with said track circuit at a point in the track section in advance of the point in the section atwhich energy is supplied to the section rails by said coding means, said detector relay having a 'nor-.

.mally released contact which is picked up when and only when there is supplied to the relay winding energy of the polarity of the energy which is supplied thereto from said second source or by operation of said coding means, and a control relay governed by said detector relay.

2. In a coded railway signaling system, in combination, a section of railway track having a first and a second track rail, a coding device at one end "of the track section having a contact continuously actuated between a first position in which it eifectively establishes connection be- I tween the section rails and a second position in which it eilectively connects a first source of energy across the section rails with the positive terminal of the source connected to the first track rail, a code following track relay at the other end of said track section operated by energy supplied over the section rails from said first source, means associated with said track relay and operative during the intervals between the impulses of energy supplied from said first source to efiectively connect a second source of energy across the section rails with the positive terminal of the source connected to the first track rail, an auxiliary relay, means for energizing said auxiliary relay when and only when the track relay is following code, coding means for at times supplying to the section rails at a point in the section removed from the track relay impulses of energy of the same polarity as that supplied from said second source, an operating circuit for said coding means established only when said auxiliary relay is released, a detector relay having a winding connected with said track circuit at a point in the track section in advance of the point in the section at which energy is supplied to thesection rails by said coding means, said detector relay having a contact whichis moved from a first to a second position when and only when there is supplied to the relay energy of the polarity which is supplied thereto from said second source or by operation of said coding means, and a control relay governed by said detector relay.

3. In a coded railway signaling system, in combination, a section of railway track, a coding device at the exit end of the section having a contact continuously actuated between a position in which it effectively connects a first source of energy across the section rails and a position in from said first source, means associated with said track relay for supplying energy to the section rails in the intervals between impulses of energy supplied from said first source, an auxiliary relay, means for energizing said auxiliary relay when and only when the track relay is operated by coded energy, each track rail of said track section having an insulated joint therein at an intermediate point in said section, coding means at said intermediate point in said track section having contacts biased to released positions in which they establish connection around the insulated joints in said track rails and movable therefrom to picked-up positions in which they connect a source of energy across the section rails in advance of the insulated joints, means governed by said auxiliary relay and controlling said coding means, and a control relay governed by said detector relay.

4. In a coded railway signaling system, in combination, a section of railway track having a first and a second track rail over which traflic normally moves in a given direction, a coding relay at the exit end of said section having a contact continuously actuated between a first position in which it effectively establishes connection between the section rails and a second position in -10 said second or third sources, and a control relay governed by said detector relay.

5. In combination, a section of railway track through which traflic normally moves in a given direction, a first coding device at the exit end of said section "having a contact continuously actuated between a position in which it effectively connects a first source of energy across the end of the section, one of the track rails of said section having an insulated joint therein at an intermediate point in said section, a second coding device having a contact biased to a position which it efiectively connects a first source oi 7 energy across the section rails with the positive terminal thereof connected to the first track rail, a code following track relay connected across the section rails at the entrance end of the section, said track relay having a normally released contact which is picked up when and only when energy flows through the relay winding from the first to the second track rail, an impulse relay having a contact biased to a released position in which it connects the track relay across the section rails and movable therefrom to a picked-up position in which it effectively connects a second source of energy across the section rails with the positive terminal thereof connected to said first track rail, means operative on release of the track relay contacts to supply to said impulse relay energy effective to momentarily pick up the contact of said impulse relay, an auxiliary relay, means for energizing said auxiliary relay .when and only when the track relay is operated by coded energy, one track rail of said track section having an insulated joint therein at an lnterme-- diate point in said track section, coding means effective when deenergized to establish connection between the portions of said track rail on opposite sides of said insulated joint and effective when energized to alternately establish connection between the portions of said track rail on opposite,

tion in advance of said insulated joint, said de-.

tector relay being of a type which is responsive to energy of one polarity only and being connected with the rails of said track section so as to be operated by energy supplied to the section rails from in which it establishes connection between the portions of saidone track rail on opposite sides of said insulated joint and movable therefrom to a position. to cause an impulse of energy to be supplied from a second source of energy to a the portion of the section rails in advance. of

said insulated joint, means eflective when said track relay is not responding to coded energy to cause the contact of said second coding device to be operated between its two positions, a code following detector relay located at a point in said section in advance of said insulated joint and operated by energy supplied over the section rails from said second source, and a control relay responsive to code following operation of said detector relay. i

6. In combination, a section of railway track through which traffic normallymoves in a given direction, one of the rails of said track section having an insulated joint therein at an intermediate point in said track section, a first coding device at the exit end of thesection having a contact continuously actuated between a .position in which it effectively connects a source of master code energy across the section rails and a position in which it effectively establishes connection between the section rails, a second coding device having a contact biased to a position in which it establishes connection between the pertionsof said one track rail on opposite sides of said insulated joint and movable therefrom to a position in which it causes an impulse of feedback energy to be supplied to the portion of. the

section rails in advance of said insulated joint;

8. code following track relay at the entrance end of said section operated by master code energy supplied over the section rails, means responsive to code following operation of said track-relay for supplying impulses of feed-back energy to the section rails in the intervals between impulses of master code energy, means effective .when said track relay is not responding tocoded energy to cause the contacts of saidsecond coding device to be operated between their two positions, a code following detector relay located at a point in said section in advance of said insulated joint and operated by feed-back energy supplied over the section rails, and a control relay responsive to code, following operation of said detector relay.

7. In combination, a section of railwaytrack I code energy across the section rails and a position in which it efiectively establishes connection between the section rails, a second coding device located at said insulated Joint-and having a contact biased to a position in which it establishes connection between the portions of said one track rail on opposite sides of said insulated joint and movable therefrom to a position in which it causes an impulse of teed-back energy to be supplied to the portion of the section rails in advance of said insulated joint, means responsive to code following operation of saidtrack relay for supplying to the section rails at the entrance end or said section an impulseotieed,

back energy during each interval between impulses of master code energy supplied over the operation of said detector relay.

ARTHUR L. .isaom. 

